This is a minimal codebase of getting grammY to work with nextjs pages directory. Please use this version of `next-connect`: `"next-connect": "^0.13.0",`

bot.ts

import { Bot, Context } from "grammy";


export const bot = new Bot<Context>(process.env.TELEGRAM_BOT_TOKEN ?? "");

start.ts

import { bot } from "path/to/bot";

const WEBAPP_URL = "" // URL to your production main site(eg. https://my-secrete-webapp.tld)

const handleGracefulShutdown = async () => {

  await bot.stop();

  process.exit();
};

if (process.env.NODE_ENV==="development") {
  // Graceful shutdown handlers
  process.once("SIGTERM", handleGracefulShutdown);
  process.once("SIGINT", handleGracefulShutdown);
}


export const startTelegramBotInDev = async () => {
  if (!bot.isInited()) {
   await bot.start();
  }
};

export const startTelegramBotInProduction = async () => {
  const webhookUrl = `${WEBAPP_URL}/api/telegram-webhook?token=${env.TELEGRAM_BOT_WEBHOOK_TOKEN}`;

    const webhookInfo = await bot.api.getWebhookInfo();

    if (webhookInfo.url !== webhookUrl) {
      await bot.api.deleteWebhook();
      await bot.api.setWebhook(webhookUrl);
    }
  } catch (_) { }
};

telegram-dev.ts

import { NextApiRequest, NextApiResponse } from "next";
import nc from "next-connect";
import { BotError } from "grammy";

import { startTelegramBotInDev } from "path/to/start";


// this is to test the bot locally by visiting http://localhost:3000/api/telegram-dev?action=start
const handler = nc<NextApiRequest, NextApiResponse>({
  attachParams: true,
  onError: (err, _req, res, next) => {
    if (err instanceof BotError) {
      res.status(200).send({});
    } else {
      console.error(err);
      res.status(500).end("Something broke!");
    }
    next();
  },
})
  .get((req, _res, next) => {
    if (process.env.NODE_ENV==="development") {
      next();
    }
  })
  .get(async (req: NextApiRequest, res: NextApiResponse) => {
    try {
      if (req.query && req.query.action !== "start") {
        res.status(500).send({ error: { message: "Wrong gateway." } });
        return;
      }

      await startTelegramBotInDev();
      res.status(200).send("ok");
    } catch (error) {
      res.status(500).json({ error });
    }
  });

export default handler;
  
 // path: /pages/api/telegram-dev.ts

telegram-webhook.ts

import { NextApiRequest, NextApiResponse } from "next";
import nc from "next-connect";
import { BotError, webhookCallback } from "grammy";

import { bot } from "path/to/bot";
import { startTelegramBotInProduction } from "path/to/start";

const isProd = process.env.NODE_ENV === "production"

const handler = nc<NextApiRequest, NextApiResponse>({
  attachParams: true,
  onError: (err, _req, res, next) => {
    if (err instanceof BotError) {
      res.status(200).send({});
    } else {
      res.status(500).end("Something broke!");
    }
    next();
  },
})
  .post((req, _res, next) => {
    if (req.query && req.query.token === process.env.TELEGRAM_BOT_WEBHOOK_TOKEN) {
      next();
    }
  })
  .post(webhookCallback(bot, "next-js"))
  .get(async (req, res) => { 
  // this is used to automatically setup your webhook by visiting https://my-secrete-webapp.tld/api/telegram-webhook?token=[YOUR-BOT-TOKEN]
  // replace [YOUR-BOT-TOKEN] with your telegram bot token
  // only do so after you have deployed your bot in production
    try {
      if (process.env.NODE_ENV !=="production" || (req.query && req.query.token !== process.env.TELEGRAM_BOT_WEBHOOK_TOKEN)) {
        return res.status(500).send({ error: { message: "Wrong gateway." } });
      }

      await startTelegramBotInProduction();
    } finally {
      return res.status(200).send("ok");
    }
  });

export default handler;
  
  // path: /pages/api/telegram-webhook.ts

typo in start.ts#L6: console.info

typo in start.ts#L6: console.info

Thanks! I fixed it and removed non important code from the entire structure so as to minimize unexpected errors

did you try this with app directory?